These pills are for bumpy, oozing things.
These pills are for puffy, scaly things.
These pills are for loose, smelly things.
These pills are for what YOU have.

The drawing certainly does not make it look like “what you have” includes all the rest. Anyway, why even have the other 3 kinds of pills? Everybody is going to buy the pills for “what you have” and not even bother with the rest. Even if you had bumpy, oozing things, would you buy the pills for “bumpy, oozing things” or the pills for “what YOU have”?

I saw the joke as a sort of reluctance to admit that you have certain embarrassing problems. A conversation to heal what ails you might go like this:

YOU: I have a problem with something.
PHARMACIST: Is it a bumpy, oozing thing?
YOU: Not at all!
PHARMACIST: Is it a puffy, scaly thing?
YOU: Definitely not!
PHARMACIST: Is it a loose, smelly thing?
YOU: Never in a million years!
PHARMACIST: Then this fourth group of medication is just the thing for you!